The proposed work is designed to elucidate the metabolism of five 14C-labeled environmental carcinogens (aniline hydrochloride, three aniline derivatives (5-chloro-2-methylaniline, 2-methyl-5-nitroaniline, and 4-amino-2-nitrophenol) and 2,4,-dinitrotoluene) in (a) animal species (mice or rats) with demonstrated susceptibility and insusceptibility to these agents; (b) another untested species of experimental animal (hamster); and (c) human liver. The mechanisms of action of these agents will also be investigated. Appropriate unlabeled N-hydroxy, nitroso, and azo derivatives will be chemically synthesized, as necessary, to be used as substrates for enzymatic reactions and as standards for structural confirmation of expected metabolites. Microsomal enzymes possibly involved in the activation of the agents will be assayed, and microsomal metabolites will be identified and quantitated. Possible steps involved in further activation, such as enzymatic sulfation or acetylation, will also be assessed. Following administration of oral doses of the labeled compounds to the experimental animals, blood levels and urinary excretion of the intact compounds and their metabolites will be measured, and the pharmacokinetics of the compounds will be determined. The metabolic and pharmacokinetic studies will utilize established methodology (TLC, HPLC, and mass spectrometry) for isolation, purification, identification, and quantitation of parent agents and their metabolites. Metabolite profiles for blood and urine will be determined, and structural identification of major metabolites will be attempted. The irreversible binding of 14C to RNA, DNA, and protein in vivo will be measured. The effect of repeated doses on microsomal metabolism, on blood and urinary metabolites, on pharmacokinetics, and on binding to macromolecules will be determined. We expect that, for the susceptible species, metabolic prodcution of N-hydroxy compounds will occur to a greater extent and that the resulting activated compounds, with or without further metabolism, will bind to cellular macromolecules to a greater extent than for the species not susceptible to the carcinogens. These studies should allow a basis for prediction of carcinogenicity to the untested species and to man.